The Change in Human Microvascular Function and its Relationship to Plasma Epoxide Content After Short‐Term Walnut Intake

Abstract

Walnuts are a source of alpha‐linolenic acid (ALA) and linoleic acid (LA). We examined the effects of short‐term walnut intake on the reactive hyperemia index (RHI), a measure of microvascular function. We hypothesized that 4 weeks of 40g/day of walnuts would improve RHI compared to 5g/day of walnuts in hypercholesterolemic postmenopausal women. Microvascular function is influenced, in part, by locally produced vasodilators, such as nitric oxide and endothelial‐derived hyperpolarizing factor (EDHF). Putative EDHF include cytochrome P450 epoxides of arachidonic acid (AA) known as the EpETrEs. Epoxides are also derived from ALA (EpODE) and LA (EpODE); however, their vascular influence is currently undefined. Four weeks of 40g/day of walnut intake increased RHI compared to 5g/day (2.61 ± 0.10 versus 2.24 ± 0.12, respectively, p = 0.027). Plasma EpODE and EpOME were significantly increased with 40g/day compared to 5g/day of walnut intake. The total change in plasma epoxides was strongly associated with the change in RHI (r=0.65, p = 0.002). There was a strong association between the change in EpODE, EpOME, and EpETrE, as well as, these epoxides and the change in RHI (|r|=0.56, p < 0.01); with the strongest association observed for 14(15)‐EpETrE (r=0.72, p < 0.001). These data are consistent with reports of improved vascular function with walnut consumption, and provide new insights into potential relationships between changes in microvascular function and plasma epoxides after walnut intake.